From e0343fca54d6a779fd94df9863db2b28bb9ba332 Mon Sep 17 00:00:00 2001
From: Joachim Van Herwegen <joachimvh@gmail.com>
Date: Tue, 23 Jun 2020 10:04:51 +0200
Subject: [PATCH] feat: add response description interface

---
 src/ldp/AuthenticatedLdpHandler.ts            | 13 ++++++-------
 src/ldp/http/ResponseWriter.ts                |  4 ++--
 src/ldp/operations/OperationHandler.ts        |  3 ++-
 src/ldp/operations/ResponseDescription.ts     | 10 ++++++++++
 test/unit/ldp/AuthenticatedLdpHandler.test.ts |  2 +-
 5 files changed, 21 insertions(+), 11 deletions(-)
 create mode 100644 src/ldp/operations/ResponseDescription.ts

diff --git a/src/ldp/AuthenticatedLdpHandler.ts b/src/ldp/AuthenticatedLdpHandler.ts
index f5c626a85..57bcf5619 100644
--- a/src/ldp/AuthenticatedLdpHandler.ts
+++ b/src/ldp/AuthenticatedLdpHandler.ts
@@ -9,6 +9,7 @@ import { OperationHandler } from './operations/OperationHandler';
 import { PermissionSet } from './permissions/PermissionSet';
 import { PermissionsExtractor } from './permissions/PermissionsExtractor';
 import { RequestParser } from './http/RequestParser';
+import { ResponseDescription } from './operations/ResponseDescription';
 import { ResponseWriter } from './http/ResponseWriter';
 
 /**
@@ -87,15 +88,15 @@ export class AuthenticatedLdpHandler extends HttpHandler {
    */
   public async handle(input: { request: HttpRequest; response: HttpResponse }): Promise<void> {
     let err: Error;
-    let operation: Operation;
+    let description: ResponseDescription;
 
     try {
-      operation = await this.runHandlers(input.request);
+      description = await this.runHandlers(input.request);
     } catch (error) {
       err = error;
     }
 
-    const writeData = { response: input.response, operation, error: err };
+    const writeData = { response: input.response, description, error: err };
 
     return this.responseWriter.handleSafe(writeData);
   }
@@ -107,13 +108,11 @@ export class AuthenticatedLdpHandler extends HttpHandler {
    *
    * @returns A promise resolving to the generated Operation.
    */
-  private async runHandlers(request: HttpRequest): Promise<Operation> {
+  private async runHandlers(request: HttpRequest): Promise<ResponseDescription> {
     const op: Operation = await this.requestParser.handleSafe(request);
     const credentials: Credentials = await this.credentialsExtractor.handleSafe(request);
     const permissions: PermissionSet = await this.permissionsExtractor.handleSafe(op);
     await this.authorizer.handleSafe({ credentials, identifier: op.target, permissions });
-    await this.operationHandler.handleSafe(op);
-
-    return op;
+    return this.operationHandler.handleSafe(op);
   }
 }
diff --git a/src/ldp/http/ResponseWriter.ts b/src/ldp/http/ResponseWriter.ts
index c6e9769de..ac5bed3d8 100644
--- a/src/ldp/http/ResponseWriter.ts
+++ b/src/ldp/http/ResponseWriter.ts
@@ -1,9 +1,9 @@
 import { AsyncHandler } from '../../util/AsyncHandler';
 import { HttpResponse } from '../../server/HttpResponse';
-import { Operation } from '../operations/Operation';
+import { ResponseDescription } from '../operations/ResponseDescription';
 
 /**
  * Writes to the HttpResponse.
  * Response depends on the operation result and potentially which errors was thrown.
  */
-export type ResponseWriter = AsyncHandler<{ response: HttpResponse; operation: Operation; error?: Error }>;
+export abstract class ResponseWriter extends AsyncHandler<{ response: HttpResponse; description?: ResponseDescription; error?: Error }> {}
diff --git a/src/ldp/operations/OperationHandler.ts b/src/ldp/operations/OperationHandler.ts
index 405be2f10..b58ddf3a2 100644
--- a/src/ldp/operations/OperationHandler.ts
+++ b/src/ldp/operations/OperationHandler.ts
@@ -1,7 +1,8 @@
 import { AsyncHandler } from '../../util/AsyncHandler';
 import { Operation } from './Operation';
+import { ResponseDescription } from './ResponseDescription';
 
 /**
  * Handler for a specific operation type.
  */
-export abstract class OperationHandler extends AsyncHandler<Operation> {}
+export abstract class OperationHandler extends AsyncHandler<Operation, ResponseDescription> {}
diff --git a/src/ldp/operations/ResponseDescription.ts b/src/ldp/operations/ResponseDescription.ts
new file mode 100644
index 000000000..3958fdc2c
--- /dev/null
+++ b/src/ldp/operations/ResponseDescription.ts
@@ -0,0 +1,10 @@
+import { Representation } from '../representation/Representation';
+import { ResourceIdentifier } from '../representation/ResourceIdentifier';
+
+/**
+ * The result of executing an operation.
+ */
+export interface ResponseDescription {
+  identifier: ResourceIdentifier;
+  body?: Representation;
+}
diff --git a/test/unit/ldp/AuthenticatedLdpHandler.test.ts b/test/unit/ldp/AuthenticatedLdpHandler.test.ts
index 02bdec362..efa1d61a5 100644
--- a/test/unit/ldp/AuthenticatedLdpHandler.test.ts
+++ b/test/unit/ldp/AuthenticatedLdpHandler.test.ts
@@ -44,7 +44,7 @@ describe('An AuthenticatedLdpHandler', (): void => {
 
     await expect(handler.handle({ request: 'request' as any, response: 'response' as any })).resolves.toEqual('response');
     expect(responseFn).toHaveBeenCalledTimes(1);
-    expect(responseFn).toHaveBeenLastCalledWith({ response: 'response', operation: 'parser' as any });
+    expect(responseFn).toHaveBeenLastCalledWith({ response: 'response', description: 'operation' as any });
   });
 
   it('sends an error to the output if a handler does not support the input.', async(): Promise<void> => {